Porphyria cutanea tarda, also known as PCT, is the most common form of porphyria. The skin and liver are mainly affected by the symptoms. The disease is easily treatable, even if the underlying disorder is incurable.
What is porphyria cutanea tarda?
Porphyria cutanea tarda is one of the so-called porphyrias and is even the most common subtype of these diseases. Porphyria is caused by the build-up of intermediate products that are formed during the synthesis of hemoglobin. Hemoglobin synthesis proceeds in several reaction steps. See howsmb for LEOPARD Syndrome Definition and Meaning.
After each reaction step, a special intermediate product is formed, which is converted again in a subsequent reaction. If this subsequent reaction does not take place or takes place slowly, the respective reaction product accumulates and is stored in various organs of the body. The type of porphyria thus depends on which intermediate product of heme synthesis is involved.
In porphyria cutanea tarda, disturbances occur in the fifth reaction step of hemoglobin synthesis. The enzyme responsible, uroporphyrinogen decarboxylase, catalyzes the decarboxylation of uroporphyrinogen III to coproporphyrinogen III. Inactivity or deficiency of this enzyme leads to porphyria cutanea tarda.
Uroporphyrinogen III accumulates and is deposited in the skin and liver. In the term porphyria cutanea tarda, the word “cutanea” means skin and the word “tarda” means delayed. The disease breaks out with a time delay after the beginning accumulation of the intermediate product.
Causes
The immediate cause of porphyria cutanea tarda is therefore a weakness in the enzyme uroporphyrinogen decarboxylase. This can be due to a deficiency or an inability of this enzyme to function. In about 20 percent of cases, there is a mutation in the UROD gene, which codes for uroporphyrinogen decarboxylase. The corresponding gene is located on chromosome 1. The genetically determined porphyria cutanea tarda is inherited in an autosomal dominant manner.
However, in the vast majority of those affected, porphyria cutanea tarda is acquired. Certain underlying diseases of the liver can impair the function of uroporphyrinogen decarboxylase. The liver is the central metabolic organ. Complex reactions take place here.
In diseases of the liver, however, certain reaction chains can be interrupted, so that the entire metabolism is also subject to disturbances. In the case of uroporphyrinogen decarboxylase, this can mean that this enzyme is either no longer produced or only produced to a reduced extent. Furthermore, its functionality can also be limited if subsequent reaction chains no longer work.
Liver damage caused by the influence of alcohol, medication, other toxins or viral infections such as hepatitis C can also cause or promote porphyria cutanea tarda. The functional restriction of uroporphyrinogen decarboxylase causes the accumulation of heme synthesis precursor uroporphyrinogen III.
This intermediate is preferentially stored in the skin and liver. Uroporphyrinogen III can absorb sunlight and thereby induce the formation of oxygen radicals. These radicals are very reactive and destroy the skin when exposed to light.
Symptoms, Ailments & Signs
Therefore, the central symptom of porphyria cutanea tarda is the photosensitivity of the skin. Skin lesions and blisters form in areas exposed to UV radiation from the sun. The face, legs or backs of the hands are often affected. In addition to larger bubbles, smaller liquid-filled bubbles also form there.
In addition, the skin is very brittle, and the smallest injuries can immediately lead to blisters. Small, white cysts, which are also known as milia, develop with a time lag. The milia form at the exits of the sebaceous glands and are only a side effect. They have more of a cosmetic meaning. However, the constant damage to the skin caused by bursting blisters is medically significant.
Here there is a constant risk of developing infections. Other skin symptoms include pigment shifts with areas of increased and decreased pigmentation, increased hair on the forehead and face (hypertrichosis), a brownish complexion and thickening of the skin. Porphyrin deposits in the liver lead to hepatomegaly (enlarged liver).
The liver values are significantly increased. At the same time, the risk of liver cancer increases. If there is an underlying liver disease, however, the liver symptoms cannot be clearly attributed to porphyria. The urine is often pink to brown in color due to porphyria excretion.
Diagnosis & course of disease
Porphyria cutanea tarda is diagnosed by determining the porphyria in blood, urine and stool. With this examination, acquired forms of porphyria cutanea tarda can also be distinguished from genetically determined forms. An increased excretion of isocoproporphyrin in the stool indicates the genetic variant.
Complications
In most cases, those affected by porphyria cutanea tarda suffer from various skin complaints. This can be associated with restrictions in the everyday life of the patient. Above all, the reduced aesthetics of the person concerned often leads to inferiority complexes or reduced self-esteem. Sometimes depression or other psychological upsets can also occur.
However, the underlying disease of porphyria cutanea tarda cannot be cured, so that only the symptoms of this disease can be limited. Porphyria cutanea tarda can also cause liver cancer. The liver values themselves are elevated in this disease, which can lead to jaundice. In the worst case, the liver has to be completely removed and replaced with a donor organ.
Likewise, patients with porphyria cutanea tarda suffer from various pigment disorders, which can also have a very negative effect on their quality of life. Porphyria cutanea tarda can be treated with the help of hormones. However, complete healing is not achieved. Regular blood sampling is also necessary to prevent high iron levels. As a rule, this disease also significantly reduces the life expectancy of the patient.
When should you go to the doctor?
Porphyria cutanea tarda should always be examined and treated by a doctor. This disease does not heal itself and in many cases the symptoms worsen. As a rule, the disease cannot be completely cured either, since it can only be treated symptomatically.
The doctor should be consulted for porphyria cutanea tarda when blisters and lesions form on the skin. UV radiation in particular can promote these symptoms. If the skin problems occur suddenly and do not go away on their own, you must consult a doctor. Likewise, liver problems can indicate porphyria cutanea tarda and should be examined by a doctor.
The disease is usually treated by a dermatologist. However, since the risk of liver cancer is also significantly increased, regular check-ups are very useful. In most cases, however, the patient’s life expectancy is not negatively affected by the disease.
Treatment & Therapy
The porphyria cutanea tarda can usually not be treated causally. With various treatment methods, however, it is possible to achieve an extensive freedom from symptoms. For some patients, it is enough to avoid alcohol, iron preparations, certain medications or hormone treatment with estrogens to drastically improve the symptoms.
Since too much iron is also stored in the liver in porphyria cutanea tarda, bloodletting is used at specific time intervals to try to normalize the iron level again. The symptoms also improve. Bloodletting also protects against recurrences. Severe cases can also be treated with chloroquine. This active substance forms complexes with porphyrins and enables its rapid excretion in the urine.
Prevention
Because acquired porphyria cutanea tarda is caused by liver disease, the best way to prevent it is to avoid alcohol and drug abuse. It was found that the majority of patients with acquired porphyria cutanea tarda had liver damage caused by alcohol.
Aftercare
After the successful treatment of porphyria cutanea tarda, comprehensive follow-up measures should be taken to prevent a new outbreak of the disease and to avoid long-term damage. These consist primarily of abstaining from alcohol, certain medications that affect the metabolism, and not administering artificial estrogen.
In addition, the supply of iron as a dietary supplement should be avoided. An additional low-iron diet can also be helpful in preventing the recurrence of porphyria cutanea tarda. However, this should always be discussed with the doctor treating you.
Since the iron levels in the blood must be checked regularly during such a diet in order to avoid the development of iron deficiency anemia, regular consultation of both parties is required. Such a diet is urgently needed, especially if there is also an iron storage disease. In addition, the liver should be examined regularly using imaging methods (ultrasound, MRT, CT) in order to detect complications in the liver at an early stage.
To check the liver function, regular examinations of the liver values in the blood are also necessary. In addition, the porphyrin levels in the blood, urine and stool should be checked regularly in order to detect a renewed outbreak of the disease at an early stage. If diabetes mellitus is the underlying disease, it should be treated separately and comprehensively, since untreated diabetes mellitus increases the likelihood of a new outbreak of porphyria cutanea tarda.
You can do that yourself
Those affected with porphyria cutanea tarda have very few options for self-help. As a rule, the disease cannot be treated causally, but only symptomatically, so that the patient is dependent on lifelong therapy.
In some cases, a change in diet can be sufficient to combat porphyria cutanea tarda. The person concerned should generally avoid alcohol and nicotine. Iron preparations should also no longer be taken, although of course you should consult your doctor. The iron level can be normalized by bloodletting, which can only be carried out by a doctor. In the event of drug abuse or alcohol abuse, withdrawal should be carried out. If the patient cannot carry out the withdrawal himself, he can also be admitted to a clinic.
In the case of porphyria cutanea tarda, contact with other people affected by the disease often proves to be very useful, so that information is exchanged. A retrospective treatment of the liver damage is not possible, so that a reduced life expectancy of the patient is to be expected in the case of alcohol abuse.
